Ancient crinoid toxins/pigments were only discovered after careful extraction

Looking at fossils of so-called "sea lillies" or crinoids, observers have sometimes noted a curious thing -- they're often different colors than the base rock. For example, one sample recent examined by Ohio State University geology Ph.D student Christina O'Malley was a light blue gray, another was dark grey, and a third was cream colored.

I. A Shocking Discovery

Grinding up small bits of the colorful fossilized sea critters and analyzing their chemistry with a gas chromatograph mass spectrometer, Ms. O'Malley made a surprising discovery. The fossilization had preserved quinones, a type of aromatic biomolecule that serve both as a pigment, and sometimes as a toxin to ward off predators.

The discovery was unusual because aromatic molecules -- which also included molecules like dioxyribonucleic acid (DNA) -- were thought to be almost entirely broken down after just millions of years.

The key to the preservation was the mineral calcite that permeated into the sea creature's pores and locked in the organics during the fossilization. And while many fossils are exposed to harsh conditions -- volcanism or mountain range shifts -- the crinoids found in Ohio, Indiana, and Iowa digs were exposed to relatively gentle conditions.

This allowed the fragile biomolecules to stand the test of time.

II. Biochemicals Could be Useful in IDing Species

Ms. O'Malley and her advisor Earth SciencesProfessor William Ausich are confident that the quinones were indeed produced by the ancient crinoids as they are similar in composition to quinone pigments produced by the crinoids modern-day living relatives.

Quinones (purple) are found in modern Crinoids as well. [Image Source: Biochimica]

The Ph.D student says her predecessors lacked the tools to perform that kind of analysis, commenting, "People noticed the color differences 100 years ago, but no one ever investigated it. The analytical tools were not available to do this kind of work as they are today."

Professor Ausisch cheered the discovery, suggesting it could provide clues about ancient genetics. He comments, "These molecules are not DNA, and they'll never be as good as DNA as a means to define evolutionary relationships, but they could still be useful. We suspect that there's some kind of biological signal there -- we just need to figure out how specific it is before we can use it as a means to track different species."

Those clues could give scientists better perspective on what life was like in North American 350 million years ago in the Carboniferous Period, a time when vast seas covered North America.